25 words

Your sentences are too long. Shorten your sentences!

As an editor, I’m more descriptive instead of prescriptive. I know that audience, context and genre shape meaning. Language is a shifting beast–but more problematically than that, the so-called ‘rules’ of grammar and writing are arbitrary, classist, colonialist, even wrong.

But I’m still going to tell you to shorten your sentences. Aim to keep them no longer than 25 words. Here’s why & how.

When your sentences are shorter, they’re easier to follow.

In 1948, Rudolph Flesch published his “New Readability Yardstick” in the Journal of Applied Psychology. Since then, all kinds of linguists, educators, researchers of all stripes have debated the best way to measure a text’s readability. If you’ve ever played around with a file’s readability score in Microsoft Word, you may have seen the “Flesch Reading Ease test” and the “Flesch-Kincaid Grade Level test”–both of which are in reference to this 1948 journal article.

70-year-old science is old science. It’s been debated, debunked, updated, overturned.

But Flesch was one of the first to argue that longer sentences are harder to read. Whatever nuances of his readability index have been revised, shorter sentences still remain clearer than longer ones.

Here’s why writers of academic research need to write shorter sentences:

  • Your reader is skimming your text. Universities teach their students to skim and to scan–to read strategically rather than investing the time to review every word on a page. As a scholar moves from undergraduate to graduate student to independent researcher, they fine-tune these skills, developing high literacy within their specialized field.
  • Your reader may be reading on a screen, and eye-tracking studies have shown us that high-literacy readers tend to scan screens for the information they’re seeking, rather than reading from top-to-bottom, left-to-right.
  • Your reader is a little bit drunk. Well, not really, but if they’re tired from overwork, family responsibilities, stress, or ill-health, their moderate fatigue could leave them more impaired than a driver over the legal speeding limit. What if your ten-page grant proposal is the eighteenth of the twenty they need to read?

My tool for identifying overly-long sentences is writingwellishard.com. Cut and paste your text into the text box, and the tool will highlight for you the longest sentence in your draft. It will also show your draft’s average sentence length.

If you have a lot of long sentence, start by chopping up the sentences in regions of key strategic importance: topic sentences, introductory paragraphs, discussion, conclusion. Then, use my “is” tip to shorten wordy phrasing. Next, integrate some active voice in with passive voice constructions. Slowly, you’ll drop your average sentence length.

Shortening your sentences makes your writing easier to digest. Your reader will be less likely to leave your text without having taken your point. Being understood on the first skim, scan, or–if you’re lucky–close read makes your knowledge easier to cite, fund, or put into practice.

So, sure, yes, descriptive-editor me says that context matters and there are no real rules and you just gotta be you, man. “Shorter is better” is an oversimplification: I know, I agree.

But prescriptivist me? That me wants you to be read and understood. So that me says:

Your sentences should be 25 words, max. To identify the longest sentence in a sample of your writing, and to see the average length of your sentences, visit writingwellishard.com.

PS: OK, fine, some sentence length variety is allowed. Keep it interesting. But if you have too many 25+ word sentences, you’ll lose your readers.

PPS: the average sentence length in this blog post is 13.15 words.


In a 2013 journal article in Measurement, Barbic et al. compared used a range of readability tools to assess the readability of commonly read journals in psychiatry, and contrasted them against some of the top medical journals: the New England Journal of Medicine (5-year Impact Factor 51.7), The Lancet (IF 36.4), and the Journal of the American Medical Association (IF 29.3). Of these, the average number of word per sentence were all under 25:

  • New England Journal of Medicine: average 24.8 words per sentence
  • The Lancet: average 23.8 words per sentence
  • Journal of the American Medical Association: average 19.0 words per sentence

One of Barbic et al.’s biggest take-aways: the norm for writing in your field may not be the way you need to write when addressing a broader audience of readers outside of your specific field.

Barbic, Skye P., et al. “Readability assessment of psychiatry journals.” Measurement 24 (2013): 26.


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